Geoscience Reference
In-Depth Information
Figure 2.11.
Major surface (hatched arrows) and deep currents (thin black arrows) of
the Arctic Ocean, along with the locations of discharge from the four largest Arctic-
draining rivers (Ob, Yenisey, Lena, and Mackenzie). Shading corresponds to bathymetry
(courtesy of G. Holloway, Institute of Ocean Sciences, Sidney, BC).
the oceanic and terrestrial domains, there must be a compensating convergence
of water vapor into the atmospheric domain, estimated at about 4,900 km
3
. The
inflow of low-salinity water through the Bering Strait is estimated at 2,500 km
3
.
The major outflows of freshwater from the ocean are through the Fram Strait, both
as sea ice and as fairly low-salinity liquid water (less than the 34.8 reference),
and through the channels of the Canadian Arctic Archipelago as low-salinity liq-
uid water. There are a number of smaller terms, some of which are not shown in
the schematic. Note that while the Barents Sea Branch and the West Spitzbergen
Current represent water inflows to the Arctic, in the framework of the freshwater
balance adopted here, they count as freshwater sinks because the mean salinity of
these inflows is higher than the adopted reference salinity. Although there is no
reason that the freshwater budget is ever in a steady state, the oceanic imbalance
of 700 km
3
, is within the error bounds of the data sources and hence indistinguish-
able from zero. Note that the terrestrial budget is also not closed. On the basis of
the ratio between storage and inputs, freshwater in the Arctic Ocean has a mean
residence time of about a decade. This is understood in that annual freshwater
input, while large (8,500 km
3
), is an order of magnitude smaller than oceanic
freshwater storage of 84,000 km
3
. Freshwater in the atmosphere, as water vapor,
has a residence time of only about a week.
